There is a need in the industry for large port count optical switches. These switches are typically designed to be single mode with broad optical bandwidth and a multitude of input and output fibers. Multiple practical techniques exist for making smaller port count switches (e.g., 2×2, 4×4, 8×8, 16×16) but most of these techniques do not scale well at or above 32×32. Specifically, performance parameters of interest start become more difficult to achieve, including but not limited to loss, crosstalk and switching speed. Switches are needed that have 128×128 ports or higher with low loss and switching speeds significantly faster than current generation switches.
Most high port count (e.g., greater than 128) switches use a 3D MEMs architecture, where a 2 axis tilt mirror is used to steer a free space beam from one input port to a second mirror that then steers the beam to a second output port. Due to the inherent modal propagation in free space, these switches are difficult to scale without sacrificing switching time. This is fundamentally due to the larger beam requirements and therefore larger mirrors as the port count grows.